It is forbidden to eat, drink and have intercourse during the days of Ramadan. Doing any of these during the fast is considered as disobedience to God. Messenger Muhammad (pbuh) said:
“Whoever breaks a fast in Ramadan without an excuse or sickness, a whole life of fast will not replace that broken one.” (Bukhari, Sawm/Fast, 29)
A person in this situation should immediately repent and ask God for forgiveness. It doesn’t require expiation or compensation, and it can not be replaced with anything else.